Technical Field
The present disclosure relates to solid state image sensors in digital imaging systems, more particularly to an image quality learning method and system for solid state image sensors.
Description of the Related Art
Solid state image sensors normally include an array of pixels arranged in rows and columns which form a bi-dimensional image representation. An image is read out, row by row, via an array of Analogue to Digital Converters (ADC). Light is incident on these pixels for a time called integration time and the resulting charge is converted into a voltage before being read out. The readout process includes converting the analogue voltage to a digital value and then processing the collected digital values in order to construct an image.
The digital values in the constructed image will be an imperfect representation of the scene. The Image Quality (IQ) of a constructed image measures the degradation from what is considered by the system as the optimal image. The sensor is designed and set up in such a way that it reduces the various factors of degradation. Such an optimal image is determined within the system by comparison of the selected measured parameters with a determined value or range of values.
Commercially available machine vision systems use an Image Quality mechanism which implements algorithms to automatically determine the optimal setting of image parameters. Each algorithm calculates a set of metrics from the image data to quantify the current performance of the camera system. Examples of IQ metrics include focus, brightness, white balance, etc. These metrics are normally calculated over several frames, so that the algorithm can “search” for the optimal settings for the camera system. While working reasonably well, these algorithms often take several frames to “converge” to the correct settings, because the optimal convergence point cannot be calculated with information from just one frame. Therefore the user might be obliged to wait for some time (e.g., a few seconds) to get the image at a satisfactory quality level. This delay even if limited to a couple of seconds could be annoying and could represent the difference between “capturing the moment” and losing it.